Both are a decent intermediate ski. Neither are tremendously fast but both are really stable. I found the Concept easier on the start since the Siege has a narrower footprint. If you are skiing the course at decent speed 32+ I would go for the siege, but if you are slower I would go for the concept.

its for my father in law. he's 52years old,5ft9 150 to160pnds and hes been using a 68inch taperflex g200 concave competition 31 to 33 mph with about 3 or 4 small sections removed from his line(not for sure). He's been using this ski for 35 years.is the seige fast enough? will only need a rear toe plate and a standard front boot.

When I say it's not tremendously fast I'm comparing it to brand new skis. The siege is plenty fast as it was based off the mapple (the ski Andy Mapple originally set the 1@43 off world record on) but they softened the flex to make it a little more forgiving. In all honesty the only downside to it is the narrow shape makes it a little harder to deep water start on.

Pretty much any modern ski is going to be a vast improvement over what he was on and the Siege would smoke what he is on. Is he course skiing or just free skiing?